Receptacle plug to protect appliance theft



May 21, 1963 N. c. CREMER 3,090,948

RECEPTACLE PLUG TO PROTECT APPLIANCE THEFT Filed 001'. 31, 1961 NORMAN C. CREMER INVENTOR ATTORNEY United States Patent 3,090,948 RECEPTACLE PLUG TO PROTECT APPLIANCE THEFT This invention relates generally to alarm devices, and more particularly it pertains to a power mains receptacle arrangement for giving warning upon the detachment of an appliance plug.

It is the object of this invention to provide a switch element in an electric receptacle which is operable by its mating plug.

Another object of this invention is to provide an electric circuit requiring a minimum of wiring; in combination with a novel appliance plug and mains receptacle which will sound a local or remote warning signal upon the disconnection of the plug from the receptacle.

And yet another object of this invention is to provide a dummy plug for disabling a warning system receptacle.

These and other objects and advantages of this invention will become more readily apparent and understood from the accompanying specification and single sheet of drawings in which:

FIG. 1 is a front elevation of a duplex wall receptacle incorporating features of this invention;

FIG. 2 is a cross sectional view of the receptacle of FIG. 1 taken along the line 2-2 and including a cooperative plug and alarm bell of the warning system; of this invention; and

FIG. 3 is a side elevation of a dummy plug for use in disabling the alarm system of this invention.

Referring now to the details of the drawings, in FIGS. 1 and 2 there is shown a duplex wall receptacle 10. This receptacle consists of a pair of modified spaced sockets 12 having the usual hot wire terminals 14 and ground wire terminals 16.

In the usual manner, these terminals 14 and 16 are connected to the respective hot conductor 24 and ground conductor 26 of the electric power mains.

An aperture 18 is provided in each socket 12, and it communicates to the interior thereof as best shown in FIG. 2. A resilient leaf spring 20, which is attached to the hot wire terminal 14, is located directly beneath each aperture 18 and it makes electric contact with the underside of a contact blade 22. 7

An alarm conductor 28 is routed to the desired location and it is connected to a warning device 39 such as a lamp, buzzer, or bell. The ground return wire 32 of the warning device 30 is then connected wherever convenient to the ground conductor 26 of the electric mains. Thus only one alarm wire is required for each receptacle socket 12 which is to be protected.

A special plug 34, as shown in FIG. 2, is used on the appliance, such as a radio or television set, an air conditioner, or refrigerator. When the plug 34 is inserted into its respective socket 12 to power the appliance through the usual contact pins 36, an actuator plunger 38, which is attached to the plug 34, passes through the aperture 18 and depresses the spring 2%). Consequently, as long as the plug 34 remains seated in the socket 12 the circuitry between the hot conductor 24 and the alarm conductor is interrupted.

Should there be an accidental or unauthorized removal of the plug 34, the leaf spring 2:) is no longer held depressed by the plunger 38 and hot circuit contact is made to the contact blade 22 whereby the warning device 36 gives an alarm.

When there is an authorized removal of the appliance for repairs or other reason, the alarm 30 is disabled by 3,9fi348 Patented May 21, 1953 use of a dummy plug 40 illustrated in FIG. '3. This dummy plug 40 is identical to the plug 34 having contact pins 42 and an actuator plunger 44 corresponding to the contact pins 36 and actuator plunger 38 as previously described. However, no electrical connectors are required to the contact pins 42 of this dummy plug 46.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In combination, a socket having a hot wire terminal and a ground wire terminal for connecting to hot and ground conductors, respectively, of an electric power main, said socket having a pair of openings therein for receiving spaced contact pins and an aperture extending therein, means including a resilient leaf spring attached to said hot wire terminal and located directly below said aperture, a contact blade engageable by said leaf spring, a warning device connected to said contact blade and to said ground terminal, and a plug for said socket having a pair of spaced contact pins for making contact with said hot wire and ground wire terminals and an actuator plunger for passing through said aperture in said socket for depressing said leaf spring so as to interrupt the circuitry between the hot wire terminal and said alarm device, whereby when said plug is removed from said socket, the circuitry between said hot wire terminal and said alarm device is completed-to give an indication of the removal of said plug.

2. In combination, a plug having a pair of spaced contact pins and an actuator plunger spaced from said pins, a power mains receptacle device for giving warning upon the detachment of said plug, said device consisting of at least one socket having a hot wire terminal and a ground wire terminal for connecting to hot and ground conductors, respectively, of an electric power main, said socket having a pair of spaced openings therein for receiving said spaced contact pins for connection to said hot wire and ground wire terminals and also an aperture extending therein, means including a resilient leaf spring attached to said hot wire terminal and located directly below said aperture, a contact blade engageable by said leaf spring, and a warning device connected to said contact blade and to said ground terminal, whereby when said spaced contact pins of said plug are positioned in said openings, they contact said hot wire and ground wire terminals and said actuator plunger passes through said aperture in said socket for depressing said leaf spring so as to interrupt the circuitry between said hot wire terminal and said alarm device.

3. In combination, a plug having a pair of spaced contact pins and an actuator plunger, a power mains receptacle device for giving warning upon the detachment of said plug, said device consisting of a socket having a hot wire terminal and a ground wire terminal for connecting to hot and ground conductors, respectively, of an electric power main, said socket having a pair of spaced openings and an aperture therein, a resilient leaf spring attached to said hot wire terminal and located directly below said aperture, a contact blade engageable by said leaf spring, and a warning device connected to said contact blade and to said ground terminal, said spaced contact pins of said plug contacting said hot wire and ground wire terminals and said actuator plunger passing through said aperture in said socket to depress said leaf spring so as to interrupt the circuitry between the hot wire terminal and said alarm device when said plug is assembled to said device and when said plug is removed from said socket, said circuitry between said hot wire ice " 3 terminal and said alarm device is completed to give an 1,312,191 indication of the removal 'of said plug. 2,799,852

, y 2,609,409 References Cited in the file of this patent 2,970,286

UNITED STATES PATENTS D. 151,571 Tillinghast Oct. 26, 1948 525,752

4 V V McDonnell Aug. 5, 1919 Barnes July 16, 1927 Radeke Sept. 2, 1952 Modrey Jan. 31, 1961 FOREIGN PATENTS France Oct. 9, 1920 

1. IN COMBINATION, A SOCKET HAVING A HOT WIRE TERMINAL AND A GROUND WIRE TERMINAL FOR CONNECTING TO HOT AND GROUND CONDUCTORS, RESPECTIVELY, OF AN ELECTRIC POWER MAIN, SAID SOCKET HAVING A PAIR OF OPENINGS THEREIN FOR RECEIVING SPACED CONTACT PINS AND AN APERTURE EXTENDING THEREIN, MEANS INCLUDING A RESILIENT LEAF SPRING ATTACHED TO SAID HOT WIRE TERMINAL AND LOCATED DIRECTLY BELOW SAID APERTURE, A CONTACT BLADE ENGAGEABLE BY SAID LEAF SPRING, A WARNING DEVICE CONNECTED TO SAID CONTACT BLADE AND TO SAID GROUND TERMINAL, AND A PLUG FOR SAID SOCKET HAVING A PAIR OF SPACED CONTACT PINS FOR MAKING CONTACT WITH SAID HOT WIRE AND GROUND WIRE TERMINALS AND AN ACTUATOR PLUNGER FOR PASSING THROUGH SAID APERTURE IN SAID SOCKET FOR DEPRESSING SAID LEAF SPRING SO AS TO INTERRUPT THE CIRCUITRY BETWEEN THE HOT WIRE TERMINAL AND SAID ALARM DEVICE, WHEREBY WHEN SAID PLUG IS REMOVED FROM SAID SOCKET, THE CIRCUITRY BETWEEN SAID HOT WIRE TERMINAL AND SAID ALARM DEVICE IS COMPLETED TO GIVE AN INDICATION OF THE REMOVAL OF SAID PLUG. 